I. Field of the Invention
The present invention relates to a suction nozzle to be mounted on an electric household appliance for cleaning by means of suction, such as for example a vacuum cleaner, an electric brush or a multi-purpose hoover, for sucking dust and/or fluids and/or waste from a surface. In particular, the present invention relates to a suction nozzle with a suction duct which can be detached both from a base plate and from a covering body.
II. Related Art and Other Considerations
As is known, a vacuum cleaner, an electric brush or a similar electric household appliance for cleaning by means of suction comprises a suction nozzle for sucking up dust, waste or fluids from a surface. In the field of electric household appliances, a suction nozzle is generally defined by the term “brush”. For the purposes of the present description, therefore, the terms “suction nozzle” and “brush” are considered to be equivalent. Still for the purposes of the present invention, the term “vacuum cleaner” will be used with a wider meaning so as to include all the apparatus, for professional or domestic use, which perform cleaning by means of suction. Therefore, the term “vacuum cleaner” will comprise a vacuum cleaner, an electric brush, a so-called multi-purpose hoover and a steam supply and suction apparatus.
Basically, a first known type of brush comprises a base plate which is shaped so as to have at least one base plate channel open towards the surface to be cleaned, a suction duct integral with the base plate and in fluid communication with the base plate channel and a covering body which can be joined to the base plate/suction duct assembly. The other end of the suction duct communicates with a suction tube by means of a rotatable articulated joint.
A second known type of brush comprises a base plate shaped so as to have at least one base plate channel open towards a surface to be cleaned, a covering body which can be joined to the base plate and a suction duct integral with the covering body and in fluid communication with the base plate channel. The other end of the suction duct communicates with a suction tube by means of a rotatable articulated joint.
In an embodiment of a brush of the second known type manufactured by the Applicant and marketed under the name “NE00”, a cover-piece shaped so as to cover the part of the body/channel assembly in the zone above the said duct is provided. The cover-piece is provided mainly for aesthetic reasons.
In other words, at present, the suction duct is integral, i.e. forms one piece, either with the base plate or with the covering body. Usually, the base plate, the suction duct and the body of a suction nozzle (in addition to other components) are made of a plastic material which is substantially rigid and are obtained by means of injection-moulding. Precisely for this reason it is currently considered convenient by manufacturers to mould the suction duct integrally with the base plate or the body in such a way as to limit the number of moulds and number of parts to be assembled. A brush with base plate made of metallic material is also known, but in this case the suction duct is integral with an additional plate which can be fixed to the metal plate.
For the purposes of the present patent application, the term “suction duct” will be understood as meaning a component which is substantially rigid (and not, for example, made of rubber or soft plastic material of the bellows type) and with a length greater than or equal to 2.5 cm.
The abovementioned objective of limiting the number of moulds and components to be assembled so as to form a suction nozzle is stated, for example, in the patent DE 196 17 415 C2.
On the basis of the state of the art described above, the Applicant has considered a first problem of improving the suction characteristics of a suction nozzle.
The Applicant has noted that, in a suction nozzle, two main factors help improve these characteristics: the shape of the channel (or channels) in the base plate and the shape of the suction duct, in particular its inlet mouth. While it is relatively simple to modify (modifying the mould in a corresponding manner) the shape of the base plate when the base plate is separate from the suction duct, it is extremely difficult to modify the shape of the suction duct. This is because, as mentioned above, the suction duct (substantially a shaped, curved, tubular element) is integral with the body or the base plate (which are instead shell-shaped and substantially open elements) and the mould cannot be freely modified. In other words, the design engineer is obliged to make a compromise from the point of view of the performance characteristics in order to ensure that the assembly consisting of suction duct and base plate or suction duct and body can be produced at an acceptable cost.
A further problem addressed by the Applicant is that of limiting the noise in a suction nozzle due to the passage of air. In this case also, the Applicant has discovered that, in order to limit the suction noise, it is necessary to use a suitable shape (cross-section, length and curvature) of the suction duct. Once again, however, the modifications which can actually be made are limited by the fact that the suction duct is formed as one piece with the body or with the base plate.
A further problem considered by the Applicant is that of making easier, more practical and less costly the production of a suction nozzle so that it may assume different characteristics depending on the intended use. At present, in order to manufacture a new suction nozzle with a new shape and/or which is more suitable for sucking up certain materials and/or which is more advantageously able to be associated with a given motor of the vacuum cleaner, it is necessary to provide new moulds for the suction duct/body assembly or for the suction duct/plate assembly. This is not practical, nor is it economical, and this therefore represents an obstacle to the development of new products able to satisfy specific requirements.